This application is based upon and claims the benefit of priority of Japanese Patent Application No. H.11-292606 filed on Oct. 14, 1999, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a vehicle transmission and air conditioning control system for controlling a non-stage or multi-stage transmission in which a transmission ratio may be varied continuously or stepwise according to a degree of cooling demand of an air conditioner to change a revolution of compressor.
2. Description of Related Art
Conventionally, JP-A-11-20459 describes a vehicle transmission and heating control system in which a transmission ratio is changed according to a degree of heating demand of an air conditioner to change water temperature. However, the conventional vehicle transmission control system controls the transmission ratio only corresponding to heating demand of the air conditioner, not the transmission ratio corresponding to cooling demand of the air conditioner.
In view of the matter mentioned above, an object of the present invention is to provide a vehicle transmission and air conditioning control system in which a transmission output to input ratio is controlled according to a degree of cooling demand of an air conditioner to improve cooling feeling of passengers.
It is another object of the present invention to control the transmission ratio according to the degree of cooling demand of the air conditioner so that fuel consumption of a vehicle engine may be improved.
Further object of the present invention is to control the transmission ratio so as to reduce a consumption power of a variable capacity compressor to be used in the air conditioner.
It is a furthermore object of the present invention to control the transmission ratio so as to reduce a shock caused by an intermittent operation (on and off operation) of a fixed capacity compressor to be used in the air conditioner.
To achieve the one or more objects mentioned above, in the transmission and air conditioning control system comprising an air conditioner provided with a refrigeration cycle having a compressor driven by an engine and an evaporator for cooling a passenger room, and a transmission connected between the engine and a wheel for changing an input revolution on a side of the engine to an output revolution on a side of the wheel at a transmission ratio of the input revolution to the output revolution, an electronically control device controls the transmission ratio to a reference value to be decided by the operating condition of the vehicle then prevailing and to a final value, which is higher than the reference value, when a degree of cooling demand is greater than a predetermined value.
With the system mentioned above, when the degree of cooling demand is high, for example, at a time of cool down just after starting cooling, the transmission ratio is corrected to a higher value so as to increase the vehicle engine revolution. As a result, revolution of the compressor is increased so that cooling capacity (cool down performance) of the evaporator may be improved, while the cooling feeling of a passenger is also improved.
Further, the electronically control device may control the transmission ratio to a reference value to be decided by the operating condition of the vehicle then prevailing and to a final value, which is lower than the reference value, when the degree of cooling demand decided is smaller than a predetermined value.
In this case, when the degree of cooling demand is low, for example, in a capacity control region where temperature in the passenger room reaches near a preset temperature, the transmission ratio is corrected to a lower value so as to shift the engine operation to a high efficiency range of low engine revolution and high torque. As a result, fuel consumption of the engine may be improved.
When the compressor is a variable capacity compressor whose discharge capacity is varied according to cooling degrees of the evaporator, the revolution of the compressor may reduce and the discharge capacity of the compressor may increase to improve a compression efficiency. Accordingly,consumed power of the compressor is saved to further improve the engine fuel consumption.
It is preferable, in this case, that the discharge capacity of the variable capacity compressor is used to determine the degree of cooling demand.
When the compressor is a fixed capacity compressor whose operation is intermittently controlled according to cooling degree of the evaporator, the revolution of the compressor may reduce so that on time period of the compressor operation becomes longer. Accordingly, as the intermittent operation number of the compressor becomes smaller, the shock due to the intermittent on and off operation is reduced.
It is preferred, in this case, that the operating percentage of the fixed capacity compressor is used to determine the degree of cooling demand.
Furthermore, the degree of cooling demand may be determined by at least one of a largeness of deviation between temperature of the evaporator and target temperature of the evaporator, a largeness of temperature of the passenger room, a largeness of physical quantity showing a cooling degree of the evaporator, a largeness of target temperature of air blown into the passenger room, a largeness of passenger preset temperature in the passenger room and a largeness of deviation between the temperature of the passenger room and the passenger preset temperature in the passenger room.